fix endpoint show help

endpoint show command can also work on service name or type or ID option

Change-Id: I43c8df4bc093d4130cf33fd2520736ce9077dc82

doc/source/command-objects/endpoint.rst

@@ -188,9 +188,9 @@ Display endpoint details
 .. code:: bash
 
     os endpoint show
-        <endpoint-id>
+        <endpoint>
 
 .. _endpoint_show-endpoint:
-.. describe:: <endpoint-id>
+.. describe:: <endpoint>
 
-    Endpoint ID to display
+    Endpoint to display (endpoint ID, service ID, service name, service type)

openstackclient/identity/v2_0/endpoint.py

@@ -129,8 +129,9 @@ class ShowEndpoint(command.ShowOne):
         parser = super(ShowEndpoint, self).get_parser(prog_name)
         parser.add_argument(
             'endpoint_or_service',
-            metavar='<endpoint-id>',
-            help=_('Endpoint ID to display'),
+            metavar='<endpoint>',
+            help=_('Endpoint to display (endpoint ID, service ID,'
+                   ' service name, service type)'),
         )
         return parser